Cancer survival statistics derived from population-based cancer registry data provide important measures for cancer control efforts. Follow-up data are essential to these aims, yet, relative to cancer incidence case data, these data present unique challenges associated with completeness. Accounting for medical migrations, temporary or permanent relocations motivated by the pursuit of healthcare, especially migrations among cases who leave the country and die abroad, is an especially difficult challenge. In the context of cancer surveillance, such migrations potentially impact current survival statistics that support a healthy immigrant effect, and among the US Hispanic population, has been termed the Hispanic paradox. A registry based study will be conducted to systematically examine the follow-up process and procedures, comprehensively examine the data to identify subgroups with differential follow-up data, improve follow-up data through subject tracing, and develop and propose approaches for addressing differential follow-up.